Labour-saving devices have created a generation of lardballs, and now brainwork-saving devices threaten to cripple us mentally too. Technology has moved from making things possible to making things easy, and that is as dangerous for our mental health as vegging out playing computer games and watching DVDs is for our physical health.

Take word processing. In the beginning, such software made it possible to create professional-looking documents without employing a typist. It was empowering and a huge advance. But word-processing software nowadays doesn't just enable, it takes over the job. Spelling errors are automatically corrected, grammatical mistakes are highlighted and the software even passes judgment on literary style.

Some packages even finish your words for you before you have finished typing them, something that is rightly seen as unforgivably rude in human conversation. The way software looks over our shoulders as we type, correcting and proofreading as we go, is making us lazy. Nobody reads what they have written any more. You can see the dire results in blogs all over the web. Texts are littered with "theres" that should be "theirs", and "nots" that should be "nows" - errors that spellcheckers still cannot spot. Sentences are padded with telescoping subclauses that have exactly the correct number of commas, but are completely incomprehensible.

Satnavs are just as mentally corrosive. Navigating is an essential learning process by which we build up a mental map of our environment. Research has shown that relying on a satnav allows our lazy brains to sit back and relax. At the end of a satnav-guided journey, we have no idea how we got there. The result will be a generation that is lost without guidance from the box on the dashboard.

How can adults regard themselves as independent without knowing how to get around?

Software is killing music, too. It is too easy to create music by sampling digital sounds and assembling mixes that sound good, even great, in the ambience of an Ibiza mega-club. Outside that club, it's just blah. Only in the computer age could DJs such as Fat Boy Slim be regarded as musicians. All the skills are in the software - the number of people learning how to read music or play instruments is rapidly declining.

Even the world of classical music is being deskilled. In West End theatres, orchestras are being savaged as the players in the back rows are replaced by the Sinfonia "virtual orchestra". The players at the front are retained only to give the audience the illusion that humans are in charge.

Already we live in a world where we barely have to lift a finger. Lights turn on automatically, doors open as you approach, nowhere is more than a few yards from a car parking space.

Now computers are doing the same thing for the mind. A mental obesity epidemic threatens.

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